1 /* Copyright (C) 2009 Red Hat, Inc. 2 * Copyright (C) 2006 Rusty Russell IBM Corporation 3 * 4 * Author: Michael S. Tsirkin <mst@redhat.com> 5 * 6 * Inspiration, some code, and most witty comments come from 7 * Documentation/virtual/lguest/lguest.c, by Rusty Russell 8 * 9 * This work is licensed under the terms of the GNU GPL, version 2. 10 * 11 * Generic code for virtio server in host kernel. 12 */ 13 14 #include <linux/eventfd.h> 15 #include <linux/vhost.h> 16 #include <linux/uio.h> 17 #include <linux/mm.h> 18 #include <linux/mmu_context.h> 19 #include <linux/miscdevice.h> 20 #include <linux/mutex.h> 21 #include <linux/poll.h> 22 #include <linux/file.h> 23 #include <linux/highmem.h> 24 #include <linux/slab.h> 25 #include <linux/vmalloc.h> 26 #include <linux/kthread.h> 27 #include <linux/cgroup.h> 28 #include <linux/module.h> 29 #include <linux/sort.h> 30 31 #include "vhost.h" 32 33 static ushort max_mem_regions = 64; 34 module_param(max_mem_regions, ushort, 0444); 35 MODULE_PARM_DESC(max_mem_regions, 36 "Maximum number of memory regions in memory map. (default: 64)"); 37 38 enum { 39 VHOST_MEMORY_F_LOG = 0x1, 40 }; 41 42 #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num]) 43 #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num]) 44 45 #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY 46 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq) 47 { 48 vq->user_be = !virtio_legacy_is_little_endian(); 49 } 50 51 static void vhost_enable_cross_endian_big(struct vhost_virtqueue *vq) 52 { 53 vq->user_be = true; 54 } 55 56 static void vhost_enable_cross_endian_little(struct vhost_virtqueue *vq) 57 { 58 vq->user_be = false; 59 } 60 61 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp) 62 { 63 struct vhost_vring_state s; 64 65 if (vq->private_data) 66 return -EBUSY; 67 68 if (copy_from_user(&s, argp, sizeof(s))) 69 return -EFAULT; 70 71 if (s.num != VHOST_VRING_LITTLE_ENDIAN && 72 s.num != VHOST_VRING_BIG_ENDIAN) 73 return -EINVAL; 74 75 if (s.num == VHOST_VRING_BIG_ENDIAN) 76 vhost_enable_cross_endian_big(vq); 77 else 78 vhost_enable_cross_endian_little(vq); 79 80 return 0; 81 } 82 83 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx, 84 int __user *argp) 85 { 86 struct vhost_vring_state s = { 87 .index = idx, 88 .num = vq->user_be 89 }; 90 91 if (copy_to_user(argp, &s, sizeof(s))) 92 return -EFAULT; 93 94 return 0; 95 } 96 97 static void vhost_init_is_le(struct vhost_virtqueue *vq) 98 { 99 /* Note for legacy virtio: user_be is initialized at reset time 100 * according to the host endianness. If userspace does not set an 101 * explicit endianness, the default behavior is native endian, as 102 * expected by legacy virtio. 103 */ 104 vq->is_le = vhost_has_feature(vq, VIRTIO_F_VERSION_1) || !vq->user_be; 105 } 106 #else 107 static void vhost_disable_cross_endian(struct vhost_virtqueue *vq) 108 { 109 } 110 111 static long vhost_set_vring_endian(struct vhost_virtqueue *vq, int __user *argp) 112 { 113 return -ENOIOCTLCMD; 114 } 115 116 static long vhost_get_vring_endian(struct vhost_virtqueue *vq, u32 idx, 117 int __user *argp) 118 { 119 return -ENOIOCTLCMD; 120 } 121 122 static void vhost_init_is_le(struct vhost_virtqueue *vq) 123 { 124 if (vhost_has_feature(vq, VIRTIO_F_VERSION_1)) 125 vq->is_le = true; 126 } 127 #endif /* CONFIG_VHOST_CROSS_ENDIAN_LEGACY */ 128 129 static void vhost_reset_is_le(struct vhost_virtqueue *vq) 130 { 131 vq->is_le = virtio_legacy_is_little_endian(); 132 } 133 134 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, 135 poll_table *pt) 136 { 137 struct vhost_poll *poll; 138 139 poll = container_of(pt, struct vhost_poll, table); 140 poll->wqh = wqh; 141 add_wait_queue(wqh, &poll->wait); 142 } 143 144 static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, 145 void *key) 146 { 147 struct vhost_poll *poll = container_of(wait, struct vhost_poll, wait); 148 149 if (!((unsigned long)key & poll->mask)) 150 return 0; 151 152 vhost_poll_queue(poll); 153 return 0; 154 } 155 156 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) 157 { 158 INIT_LIST_HEAD(&work->node); 159 work->fn = fn; 160 init_waitqueue_head(&work->done); 161 work->flushing = 0; 162 work->queue_seq = work->done_seq = 0; 163 } 164 EXPORT_SYMBOL_GPL(vhost_work_init); 165 166 /* Init poll structure */ 167 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, 168 unsigned long mask, struct vhost_dev *dev) 169 { 170 init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); 171 init_poll_funcptr(&poll->table, vhost_poll_func); 172 poll->mask = mask; 173 poll->dev = dev; 174 poll->wqh = NULL; 175 176 vhost_work_init(&poll->work, fn); 177 } 178 EXPORT_SYMBOL_GPL(vhost_poll_init); 179 180 /* Start polling a file. We add ourselves to file's wait queue. The caller must 181 * keep a reference to a file until after vhost_poll_stop is called. */ 182 int vhost_poll_start(struct vhost_poll *poll, struct file *file) 183 { 184 unsigned long mask; 185 int ret = 0; 186 187 if (poll->wqh) 188 return 0; 189 190 mask = file->f_op->poll(file, &poll->table); 191 if (mask) 192 vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); 193 if (mask & POLLERR) { 194 if (poll->wqh) 195 remove_wait_queue(poll->wqh, &poll->wait); 196 ret = -EINVAL; 197 } 198 199 return ret; 200 } 201 EXPORT_SYMBOL_GPL(vhost_poll_start); 202 203 /* Stop polling a file. After this function returns, it becomes safe to drop the 204 * file reference. You must also flush afterwards. */ 205 void vhost_poll_stop(struct vhost_poll *poll) 206 { 207 if (poll->wqh) { 208 remove_wait_queue(poll->wqh, &poll->wait); 209 poll->wqh = NULL; 210 } 211 } 212 EXPORT_SYMBOL_GPL(vhost_poll_stop); 213 214 static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work, 215 unsigned seq) 216 { 217 int left; 218 219 spin_lock_irq(&dev->work_lock); 220 left = seq - work->done_seq; 221 spin_unlock_irq(&dev->work_lock); 222 return left <= 0; 223 } 224 225 void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) 226 { 227 unsigned seq; 228 int flushing; 229 230 spin_lock_irq(&dev->work_lock); 231 seq = work->queue_seq; 232 work->flushing++; 233 spin_unlock_irq(&dev->work_lock); 234 wait_event(work->done, vhost_work_seq_done(dev, work, seq)); 235 spin_lock_irq(&dev->work_lock); 236 flushing = --work->flushing; 237 spin_unlock_irq(&dev->work_lock); 238 BUG_ON(flushing < 0); 239 } 240 EXPORT_SYMBOL_GPL(vhost_work_flush); 241 242 /* Flush any work that has been scheduled. When calling this, don't hold any 243 * locks that are also used by the callback. */ 244 void vhost_poll_flush(struct vhost_poll *poll) 245 { 246 vhost_work_flush(poll->dev, &poll->work); 247 } 248 EXPORT_SYMBOL_GPL(vhost_poll_flush); 249 250 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) 251 { 252 unsigned long flags; 253 254 spin_lock_irqsave(&dev->work_lock, flags); 255 if (list_empty(&work->node)) { 256 list_add_tail(&work->node, &dev->work_list); 257 work->queue_seq++; 258 spin_unlock_irqrestore(&dev->work_lock, flags); 259 wake_up_process(dev->worker); 260 } else { 261 spin_unlock_irqrestore(&dev->work_lock, flags); 262 } 263 } 264 EXPORT_SYMBOL_GPL(vhost_work_queue); 265 266 /* A lockless hint for busy polling code to exit the loop */ 267 bool vhost_has_work(struct vhost_dev *dev) 268 { 269 return !list_empty(&dev->work_list); 270 } 271 EXPORT_SYMBOL_GPL(vhost_has_work); 272 273 void vhost_poll_queue(struct vhost_poll *poll) 274 { 275 vhost_work_queue(poll->dev, &poll->work); 276 } 277 EXPORT_SYMBOL_GPL(vhost_poll_queue); 278 279 static void vhost_vq_reset(struct vhost_dev *dev, 280 struct vhost_virtqueue *vq) 281 { 282 vq->num = 1; 283 vq->desc = NULL; 284 vq->avail = NULL; 285 vq->used = NULL; 286 vq->last_avail_idx = 0; 287 vq->avail_idx = 0; 288 vq->last_used_idx = 0; 289 vq->signalled_used = 0; 290 vq->signalled_used_valid = false; 291 vq->used_flags = 0; 292 vq->log_used = false; 293 vq->log_addr = -1ull; 294 vq->private_data = NULL; 295 vq->acked_features = 0; 296 vq->log_base = NULL; 297 vq->error_ctx = NULL; 298 vq->error = NULL; 299 vq->kick = NULL; 300 vq->call_ctx = NULL; 301 vq->call = NULL; 302 vq->log_ctx = NULL; 303 vq->memory = NULL; 304 vhost_reset_is_le(vq); 305 vhost_disable_cross_endian(vq); 306 vq->busyloop_timeout = 0; 307 } 308 309 static int vhost_worker(void *data) 310 { 311 struct vhost_dev *dev = data; 312 struct vhost_work *work = NULL; 313 unsigned uninitialized_var(seq); 314 mm_segment_t oldfs = get_fs(); 315 316 set_fs(USER_DS); 317 use_mm(dev->mm); 318 319 for (;;) { 320 /* mb paired w/ kthread_stop */ 321 set_current_state(TASK_INTERRUPTIBLE); 322 323 spin_lock_irq(&dev->work_lock); 324 if (work) { 325 work->done_seq = seq; 326 if (work->flushing) 327 wake_up_all(&work->done); 328 } 329 330 if (kthread_should_stop()) { 331 spin_unlock_irq(&dev->work_lock); 332 __set_current_state(TASK_RUNNING); 333 break; 334 } 335 if (!list_empty(&dev->work_list)) { 336 work = list_first_entry(&dev->work_list, 337 struct vhost_work, node); 338 list_del_init(&work->node); 339 seq = work->queue_seq; 340 } else 341 work = NULL; 342 spin_unlock_irq(&dev->work_lock); 343 344 if (work) { 345 __set_current_state(TASK_RUNNING); 346 work->fn(work); 347 if (need_resched()) 348 schedule(); 349 } else 350 schedule(); 351 352 } 353 unuse_mm(dev->mm); 354 set_fs(oldfs); 355 return 0; 356 } 357 358 static void vhost_vq_free_iovecs(struct vhost_virtqueue *vq) 359 { 360 kfree(vq->indirect); 361 vq->indirect = NULL; 362 kfree(vq->log); 363 vq->log = NULL; 364 kfree(vq->heads); 365 vq->heads = NULL; 366 } 367 368 /* Helper to allocate iovec buffers for all vqs. */ 369 static long vhost_dev_alloc_iovecs(struct vhost_dev *dev) 370 { 371 struct vhost_virtqueue *vq; 372 int i; 373 374 for (i = 0; i < dev->nvqs; ++i) { 375 vq = dev->vqs[i]; 376 vq->indirect = kmalloc(sizeof *vq->indirect * UIO_MAXIOV, 377 GFP_KERNEL); 378 vq->log = kmalloc(sizeof *vq->log * UIO_MAXIOV, GFP_KERNEL); 379 vq->heads = kmalloc(sizeof *vq->heads * UIO_MAXIOV, GFP_KERNEL); 380 if (!vq->indirect || !vq->log || !vq->heads) 381 goto err_nomem; 382 } 383 return 0; 384 385 err_nomem: 386 for (; i >= 0; --i) 387 vhost_vq_free_iovecs(dev->vqs[i]); 388 return -ENOMEM; 389 } 390 391 static void vhost_dev_free_iovecs(struct vhost_dev *dev) 392 { 393 int i; 394 395 for (i = 0; i < dev->nvqs; ++i) 396 vhost_vq_free_iovecs(dev->vqs[i]); 397 } 398 399 void vhost_dev_init(struct vhost_dev *dev, 400 struct vhost_virtqueue **vqs, int nvqs) 401 { 402 struct vhost_virtqueue *vq; 403 int i; 404 405 dev->vqs = vqs; 406 dev->nvqs = nvqs; 407 mutex_init(&dev->mutex); 408 dev->log_ctx = NULL; 409 dev->log_file = NULL; 410 dev->memory = NULL; 411 dev->mm = NULL; 412 spin_lock_init(&dev->work_lock); 413 INIT_LIST_HEAD(&dev->work_list); 414 dev->worker = NULL; 415 416 for (i = 0; i < dev->nvqs; ++i) { 417 vq = dev->vqs[i]; 418 vq->log = NULL; 419 vq->indirect = NULL; 420 vq->heads = NULL; 421 vq->dev = dev; 422 mutex_init(&vq->mutex); 423 vhost_vq_reset(dev, vq); 424 if (vq->handle_kick) 425 vhost_poll_init(&vq->poll, vq->handle_kick, 426 POLLIN, dev); 427 } 428 } 429 EXPORT_SYMBOL_GPL(vhost_dev_init); 430 431 /* Caller should have device mutex */ 432 long vhost_dev_check_owner(struct vhost_dev *dev) 433 { 434 /* Are you the owner? If not, I don't think you mean to do that */ 435 return dev->mm == current->mm ? 0 : -EPERM; 436 } 437 EXPORT_SYMBOL_GPL(vhost_dev_check_owner); 438 439 struct vhost_attach_cgroups_struct { 440 struct vhost_work work; 441 struct task_struct *owner; 442 int ret; 443 }; 444 445 static void vhost_attach_cgroups_work(struct vhost_work *work) 446 { 447 struct vhost_attach_cgroups_struct *s; 448 449 s = container_of(work, struct vhost_attach_cgroups_struct, work); 450 s->ret = cgroup_attach_task_all(s->owner, current); 451 } 452 453 static int vhost_attach_cgroups(struct vhost_dev *dev) 454 { 455 struct vhost_attach_cgroups_struct attach; 456 457 attach.owner = current; 458 vhost_work_init(&attach.work, vhost_attach_cgroups_work); 459 vhost_work_queue(dev, &attach.work); 460 vhost_work_flush(dev, &attach.work); 461 return attach.ret; 462 } 463 464 /* Caller should have device mutex */ 465 bool vhost_dev_has_owner(struct vhost_dev *dev) 466 { 467 return dev->mm; 468 } 469 EXPORT_SYMBOL_GPL(vhost_dev_has_owner); 470 471 /* Caller should have device mutex */ 472 long vhost_dev_set_owner(struct vhost_dev *dev) 473 { 474 struct task_struct *worker; 475 int err; 476 477 /* Is there an owner already? */ 478 if (vhost_dev_has_owner(dev)) { 479 err = -EBUSY; 480 goto err_mm; 481 } 482 483 /* No owner, become one */ 484 dev->mm = get_task_mm(current); 485 worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid); 486 if (IS_ERR(worker)) { 487 err = PTR_ERR(worker); 488 goto err_worker; 489 } 490 491 dev->worker = worker; 492 wake_up_process(worker); /* avoid contributing to loadavg */ 493 494 err = vhost_attach_cgroups(dev); 495 if (err) 496 goto err_cgroup; 497 498 err = vhost_dev_alloc_iovecs(dev); 499 if (err) 500 goto err_cgroup; 501 502 return 0; 503 err_cgroup: 504 kthread_stop(worker); 505 dev->worker = NULL; 506 err_worker: 507 if (dev->mm) 508 mmput(dev->mm); 509 dev->mm = NULL; 510 err_mm: 511 return err; 512 } 513 EXPORT_SYMBOL_GPL(vhost_dev_set_owner); 514 515 struct vhost_memory *vhost_dev_reset_owner_prepare(void) 516 { 517 return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); 518 } 519 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner_prepare); 520 521 /* Caller should have device mutex */ 522 void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory) 523 { 524 int i; 525 526 vhost_dev_cleanup(dev, true); 527 528 /* Restore memory to default empty mapping. */ 529 memory->nregions = 0; 530 dev->memory = memory; 531 /* We don't need VQ locks below since vhost_dev_cleanup makes sure 532 * VQs aren't running. 533 */ 534 for (i = 0; i < dev->nvqs; ++i) 535 dev->vqs[i]->memory = memory; 536 } 537 EXPORT_SYMBOL_GPL(vhost_dev_reset_owner); 538 539 void vhost_dev_stop(struct vhost_dev *dev) 540 { 541 int i; 542 543 for (i = 0; i < dev->nvqs; ++i) { 544 if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) { 545 vhost_poll_stop(&dev->vqs[i]->poll); 546 vhost_poll_flush(&dev->vqs[i]->poll); 547 } 548 } 549 } 550 EXPORT_SYMBOL_GPL(vhost_dev_stop); 551 552 /* Caller should have device mutex if and only if locked is set */ 553 void vhost_dev_cleanup(struct vhost_dev *dev, bool locked) 554 { 555 int i; 556 557 for (i = 0; i < dev->nvqs; ++i) { 558 if (dev->vqs[i]->error_ctx) 559 eventfd_ctx_put(dev->vqs[i]->error_ctx); 560 if (dev->vqs[i]->error) 561 fput(dev->vqs[i]->error); 562 if (dev->vqs[i]->kick) 563 fput(dev->vqs[i]->kick); 564 if (dev->vqs[i]->call_ctx) 565 eventfd_ctx_put(dev->vqs[i]->call_ctx); 566 if (dev->vqs[i]->call) 567 fput(dev->vqs[i]->call); 568 vhost_vq_reset(dev, dev->vqs[i]); 569 } 570 vhost_dev_free_iovecs(dev); 571 if (dev->log_ctx) 572 eventfd_ctx_put(dev->log_ctx); 573 dev->log_ctx = NULL; 574 if (dev->log_file) 575 fput(dev->log_file); 576 dev->log_file = NULL; 577 /* No one will access memory at this point */ 578 kvfree(dev->memory); 579 dev->memory = NULL; 580 WARN_ON(!list_empty(&dev->work_list)); 581 if (dev->worker) { 582 kthread_stop(dev->worker); 583 dev->worker = NULL; 584 } 585 if (dev->mm) 586 mmput(dev->mm); 587 dev->mm = NULL; 588 } 589 EXPORT_SYMBOL_GPL(vhost_dev_cleanup); 590 591 static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) 592 { 593 u64 a = addr / VHOST_PAGE_SIZE / 8; 594 595 /* Make sure 64 bit math will not overflow. */ 596 if (a > ULONG_MAX - (unsigned long)log_base || 597 a + (unsigned long)log_base > ULONG_MAX) 598 return 0; 599 600 return access_ok(VERIFY_WRITE, log_base + a, 601 (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); 602 } 603 604 /* Caller should have vq mutex and device mutex. */ 605 static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, 606 int log_all) 607 { 608 int i; 609 610 if (!mem) 611 return 0; 612 613 for (i = 0; i < mem->nregions; ++i) { 614 struct vhost_memory_region *m = mem->regions + i; 615 unsigned long a = m->userspace_addr; 616 if (m->memory_size > ULONG_MAX) 617 return 0; 618 else if (!access_ok(VERIFY_WRITE, (void __user *)a, 619 m->memory_size)) 620 return 0; 621 else if (log_all && !log_access_ok(log_base, 622 m->guest_phys_addr, 623 m->memory_size)) 624 return 0; 625 } 626 return 1; 627 } 628 629 /* Can we switch to this memory table? */ 630 /* Caller should have device mutex but not vq mutex */ 631 static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, 632 int log_all) 633 { 634 int i; 635 636 for (i = 0; i < d->nvqs; ++i) { 637 int ok; 638 bool log; 639 640 mutex_lock(&d->vqs[i]->mutex); 641 log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL); 642 /* If ring is inactive, will check when it's enabled. */ 643 if (d->vqs[i]->private_data) 644 ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log); 645 else 646 ok = 1; 647 mutex_unlock(&d->vqs[i]->mutex); 648 if (!ok) 649 return 0; 650 } 651 return 1; 652 } 653 654 static int vq_access_ok(struct vhost_virtqueue *vq, unsigned int num, 655 struct vring_desc __user *desc, 656 struct vring_avail __user *avail, 657 struct vring_used __user *used) 658 { 659 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 660 return access_ok(VERIFY_READ, desc, num * sizeof *desc) && 661 access_ok(VERIFY_READ, avail, 662 sizeof *avail + num * sizeof *avail->ring + s) && 663 access_ok(VERIFY_WRITE, used, 664 sizeof *used + num * sizeof *used->ring + s); 665 } 666 667 /* Can we log writes? */ 668 /* Caller should have device mutex but not vq mutex */ 669 int vhost_log_access_ok(struct vhost_dev *dev) 670 { 671 return memory_access_ok(dev, dev->memory, 1); 672 } 673 EXPORT_SYMBOL_GPL(vhost_log_access_ok); 674 675 /* Verify access for write logging. */ 676 /* Caller should have vq mutex and device mutex */ 677 static int vq_log_access_ok(struct vhost_virtqueue *vq, 678 void __user *log_base) 679 { 680 size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; 681 682 return vq_memory_access_ok(log_base, vq->memory, 683 vhost_has_feature(vq, VHOST_F_LOG_ALL)) && 684 (!vq->log_used || log_access_ok(log_base, vq->log_addr, 685 sizeof *vq->used + 686 vq->num * sizeof *vq->used->ring + s)); 687 } 688 689 /* Can we start vq? */ 690 /* Caller should have vq mutex and device mutex */ 691 int vhost_vq_access_ok(struct vhost_virtqueue *vq) 692 { 693 return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) && 694 vq_log_access_ok(vq, vq->log_base); 695 } 696 EXPORT_SYMBOL_GPL(vhost_vq_access_ok); 697 698 static int vhost_memory_reg_sort_cmp(const void *p1, const void *p2) 699 { 700 const struct vhost_memory_region *r1 = p1, *r2 = p2; 701 if (r1->guest_phys_addr < r2->guest_phys_addr) 702 return 1; 703 if (r1->guest_phys_addr > r2->guest_phys_addr) 704 return -1; 705 return 0; 706 } 707 708 static void *vhost_kvzalloc(unsigned long size) 709 { 710 void *n = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT); 711 712 if (!n) 713 n = vzalloc(size); 714 return n; 715 } 716 717 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) 718 { 719 struct vhost_memory mem, *newmem, *oldmem; 720 unsigned long size = offsetof(struct vhost_memory, regions); 721 int i; 722 723 if (copy_from_user(&mem, m, size)) 724 return -EFAULT; 725 if (mem.padding) 726 return -EOPNOTSUPP; 727 if (mem.nregions > max_mem_regions) 728 return -E2BIG; 729 newmem = vhost_kvzalloc(size + mem.nregions * sizeof(*m->regions)); 730 if (!newmem) 731 return -ENOMEM; 732 733 memcpy(newmem, &mem, size); 734 if (copy_from_user(newmem->regions, m->regions, 735 mem.nregions * sizeof *m->regions)) { 736 kvfree(newmem); 737 return -EFAULT; 738 } 739 sort(newmem->regions, newmem->nregions, sizeof(*newmem->regions), 740 vhost_memory_reg_sort_cmp, NULL); 741 742 if (!memory_access_ok(d, newmem, 0)) { 743 kvfree(newmem); 744 return -EFAULT; 745 } 746 oldmem = d->memory; 747 d->memory = newmem; 748 749 /* All memory accesses are done under some VQ mutex. */ 750 for (i = 0; i < d->nvqs; ++i) { 751 mutex_lock(&d->vqs[i]->mutex); 752 d->vqs[i]->memory = newmem; 753 mutex_unlock(&d->vqs[i]->mutex); 754 } 755 kvfree(oldmem); 756 return 0; 757 } 758 759 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) 760 { 761 struct file *eventfp, *filep = NULL; 762 bool pollstart = false, pollstop = false; 763 struct eventfd_ctx *ctx = NULL; 764 u32 __user *idxp = argp; 765 struct vhost_virtqueue *vq; 766 struct vhost_vring_state s; 767 struct vhost_vring_file f; 768 struct vhost_vring_addr a; 769 u32 idx; 770 long r; 771 772 r = get_user(idx, idxp); 773 if (r < 0) 774 return r; 775 if (idx >= d->nvqs) 776 return -ENOBUFS; 777 778 vq = d->vqs[idx]; 779 780 mutex_lock(&vq->mutex); 781 782 switch (ioctl) { 783 case VHOST_SET_VRING_NUM: 784 /* Resizing ring with an active backend? 785 * You don't want to do that. */ 786 if (vq->private_data) { 787 r = -EBUSY; 788 break; 789 } 790 if (copy_from_user(&s, argp, sizeof s)) { 791 r = -EFAULT; 792 break; 793 } 794 if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { 795 r = -EINVAL; 796 break; 797 } 798 vq->num = s.num; 799 break; 800 case VHOST_SET_VRING_BASE: 801 /* Moving base with an active backend? 802 * You don't want to do that. */ 803 if (vq->private_data) { 804 r = -EBUSY; 805 break; 806 } 807 if (copy_from_user(&s, argp, sizeof s)) { 808 r = -EFAULT; 809 break; 810 } 811 if (s.num > 0xffff) { 812 r = -EINVAL; 813 break; 814 } 815 vq->last_avail_idx = s.num; 816 /* Forget the cached index value. */ 817 vq->avail_idx = vq->last_avail_idx; 818 break; 819 case VHOST_GET_VRING_BASE: 820 s.index = idx; 821 s.num = vq->last_avail_idx; 822 if (copy_to_user(argp, &s, sizeof s)) 823 r = -EFAULT; 824 break; 825 case VHOST_SET_VRING_ADDR: 826 if (copy_from_user(&a, argp, sizeof a)) { 827 r = -EFAULT; 828 break; 829 } 830 if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { 831 r = -EOPNOTSUPP; 832 break; 833 } 834 /* For 32bit, verify that the top 32bits of the user 835 data are set to zero. */ 836 if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || 837 (u64)(unsigned long)a.used_user_addr != a.used_user_addr || 838 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { 839 r = -EFAULT; 840 break; 841 } 842 843 /* Make sure it's safe to cast pointers to vring types. */ 844 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); 845 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE); 846 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) || 847 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) || 848 (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) { 849 r = -EINVAL; 850 break; 851 } 852 853 /* We only verify access here if backend is configured. 854 * If it is not, we don't as size might not have been setup. 855 * We will verify when backend is configured. */ 856 if (vq->private_data) { 857 if (!vq_access_ok(vq, vq->num, 858 (void __user *)(unsigned long)a.desc_user_addr, 859 (void __user *)(unsigned long)a.avail_user_addr, 860 (void __user *)(unsigned long)a.used_user_addr)) { 861 r = -EINVAL; 862 break; 863 } 864 865 /* Also validate log access for used ring if enabled. */ 866 if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && 867 !log_access_ok(vq->log_base, a.log_guest_addr, 868 sizeof *vq->used + 869 vq->num * sizeof *vq->used->ring)) { 870 r = -EINVAL; 871 break; 872 } 873 } 874 875 vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); 876 vq->desc = (void __user *)(unsigned long)a.desc_user_addr; 877 vq->avail = (void __user *)(unsigned long)a.avail_user_addr; 878 vq->log_addr = a.log_guest_addr; 879 vq->used = (void __user *)(unsigned long)a.used_user_addr; 880 break; 881 case VHOST_SET_VRING_KICK: 882 if (copy_from_user(&f, argp, sizeof f)) { 883 r = -EFAULT; 884 break; 885 } 886 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 887 if (IS_ERR(eventfp)) { 888 r = PTR_ERR(eventfp); 889 break; 890 } 891 if (eventfp != vq->kick) { 892 pollstop = (filep = vq->kick) != NULL; 893 pollstart = (vq->kick = eventfp) != NULL; 894 } else 895 filep = eventfp; 896 break; 897 case VHOST_SET_VRING_CALL: 898 if (copy_from_user(&f, argp, sizeof f)) { 899 r = -EFAULT; 900 break; 901 } 902 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 903 if (IS_ERR(eventfp)) { 904 r = PTR_ERR(eventfp); 905 break; 906 } 907 if (eventfp != vq->call) { 908 filep = vq->call; 909 ctx = vq->call_ctx; 910 vq->call = eventfp; 911 vq->call_ctx = eventfp ? 912 eventfd_ctx_fileget(eventfp) : NULL; 913 } else 914 filep = eventfp; 915 break; 916 case VHOST_SET_VRING_ERR: 917 if (copy_from_user(&f, argp, sizeof f)) { 918 r = -EFAULT; 919 break; 920 } 921 eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); 922 if (IS_ERR(eventfp)) { 923 r = PTR_ERR(eventfp); 924 break; 925 } 926 if (eventfp != vq->error) { 927 filep = vq->error; 928 vq->error = eventfp; 929 ctx = vq->error_ctx; 930 vq->error_ctx = eventfp ? 931 eventfd_ctx_fileget(eventfp) : NULL; 932 } else 933 filep = eventfp; 934 break; 935 case VHOST_SET_VRING_ENDIAN: 936 r = vhost_set_vring_endian(vq, argp); 937 break; 938 case VHOST_GET_VRING_ENDIAN: 939 r = vhost_get_vring_endian(vq, idx, argp); 940 break; 941 case VHOST_SET_VRING_BUSYLOOP_TIMEOUT: 942 if (copy_from_user(&s, argp, sizeof(s))) { 943 r = -EFAULT; 944 break; 945 } 946 vq->busyloop_timeout = s.num; 947 break; 948 case VHOST_GET_VRING_BUSYLOOP_TIMEOUT: 949 s.index = idx; 950 s.num = vq->busyloop_timeout; 951 if (copy_to_user(argp, &s, sizeof(s))) 952 r = -EFAULT; 953 break; 954 default: 955 r = -ENOIOCTLCMD; 956 } 957 958 if (pollstop && vq->handle_kick) 959 vhost_poll_stop(&vq->poll); 960 961 if (ctx) 962 eventfd_ctx_put(ctx); 963 if (filep) 964 fput(filep); 965 966 if (pollstart && vq->handle_kick) 967 r = vhost_poll_start(&vq->poll, vq->kick); 968 969 mutex_unlock(&vq->mutex); 970 971 if (pollstop && vq->handle_kick) 972 vhost_poll_flush(&vq->poll); 973 return r; 974 } 975 EXPORT_SYMBOL_GPL(vhost_vring_ioctl); 976 977 /* Caller must have device mutex */ 978 long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp) 979 { 980 struct file *eventfp, *filep = NULL; 981 struct eventfd_ctx *ctx = NULL; 982 u64 p; 983 long r; 984 int i, fd; 985 986 /* If you are not the owner, you can become one */ 987 if (ioctl == VHOST_SET_OWNER) { 988 r = vhost_dev_set_owner(d); 989 goto done; 990 } 991 992 /* You must be the owner to do anything else */ 993 r = vhost_dev_check_owner(d); 994 if (r) 995 goto done; 996 997 switch (ioctl) { 998 case VHOST_SET_MEM_TABLE: 999 r = vhost_set_memory(d, argp); 1000 break; 1001 case VHOST_SET_LOG_BASE: 1002 if (copy_from_user(&p, argp, sizeof p)) { 1003 r = -EFAULT; 1004 break; 1005 } 1006 if ((u64)(unsigned long)p != p) { 1007 r = -EFAULT; 1008 break; 1009 } 1010 for (i = 0; i < d->nvqs; ++i) { 1011 struct vhost_virtqueue *vq; 1012 void __user *base = (void __user *)(unsigned long)p; 1013 vq = d->vqs[i]; 1014 mutex_lock(&vq->mutex); 1015 /* If ring is inactive, will check when it's enabled. */ 1016 if (vq->private_data && !vq_log_access_ok(vq, base)) 1017 r = -EFAULT; 1018 else 1019 vq->log_base = base; 1020 mutex_unlock(&vq->mutex); 1021 } 1022 break; 1023 case VHOST_SET_LOG_FD: 1024 r = get_user(fd, (int __user *)argp); 1025 if (r < 0) 1026 break; 1027 eventfp = fd == -1 ? NULL : eventfd_fget(fd); 1028 if (IS_ERR(eventfp)) { 1029 r = PTR_ERR(eventfp); 1030 break; 1031 } 1032 if (eventfp != d->log_file) { 1033 filep = d->log_file; 1034 d->log_file = eventfp; 1035 ctx = d->log_ctx; 1036 d->log_ctx = eventfp ? 1037 eventfd_ctx_fileget(eventfp) : NULL; 1038 } else 1039 filep = eventfp; 1040 for (i = 0; i < d->nvqs; ++i) { 1041 mutex_lock(&d->vqs[i]->mutex); 1042 d->vqs[i]->log_ctx = d->log_ctx; 1043 mutex_unlock(&d->vqs[i]->mutex); 1044 } 1045 if (ctx) 1046 eventfd_ctx_put(ctx); 1047 if (filep) 1048 fput(filep); 1049 break; 1050 default: 1051 r = -ENOIOCTLCMD; 1052 break; 1053 } 1054 done: 1055 return r; 1056 } 1057 EXPORT_SYMBOL_GPL(vhost_dev_ioctl); 1058 1059 static const struct vhost_memory_region *find_region(struct vhost_memory *mem, 1060 __u64 addr, __u32 len) 1061 { 1062 const struct vhost_memory_region *reg; 1063 int start = 0, end = mem->nregions; 1064 1065 while (start < end) { 1066 int slot = start + (end - start) / 2; 1067 reg = mem->regions + slot; 1068 if (addr >= reg->guest_phys_addr) 1069 end = slot; 1070 else 1071 start = slot + 1; 1072 } 1073 1074 reg = mem->regions + start; 1075 if (addr >= reg->guest_phys_addr && 1076 reg->guest_phys_addr + reg->memory_size > addr) 1077 return reg; 1078 return NULL; 1079 } 1080 1081 /* TODO: This is really inefficient. We need something like get_user() 1082 * (instruction directly accesses the data, with an exception table entry 1083 * returning -EFAULT). See Documentation/x86/exception-tables.txt. 1084 */ 1085 static int set_bit_to_user(int nr, void __user *addr) 1086 { 1087 unsigned long log = (unsigned long)addr; 1088 struct page *page; 1089 void *base; 1090 int bit = nr + (log % PAGE_SIZE) * 8; 1091 int r; 1092 1093 r = get_user_pages_fast(log, 1, 1, &page); 1094 if (r < 0) 1095 return r; 1096 BUG_ON(r != 1); 1097 base = kmap_atomic(page); 1098 set_bit(bit, base); 1099 kunmap_atomic(base); 1100 set_page_dirty_lock(page); 1101 put_page(page); 1102 return 0; 1103 } 1104 1105 static int log_write(void __user *log_base, 1106 u64 write_address, u64 write_length) 1107 { 1108 u64 write_page = write_address / VHOST_PAGE_SIZE; 1109 int r; 1110 1111 if (!write_length) 1112 return 0; 1113 write_length += write_address % VHOST_PAGE_SIZE; 1114 for (;;) { 1115 u64 base = (u64)(unsigned long)log_base; 1116 u64 log = base + write_page / 8; 1117 int bit = write_page % 8; 1118 if ((u64)(unsigned long)log != log) 1119 return -EFAULT; 1120 r = set_bit_to_user(bit, (void __user *)(unsigned long)log); 1121 if (r < 0) 1122 return r; 1123 if (write_length <= VHOST_PAGE_SIZE) 1124 break; 1125 write_length -= VHOST_PAGE_SIZE; 1126 write_page += 1; 1127 } 1128 return r; 1129 } 1130 1131 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 1132 unsigned int log_num, u64 len) 1133 { 1134 int i, r; 1135 1136 /* Make sure data written is seen before log. */ 1137 smp_wmb(); 1138 for (i = 0; i < log_num; ++i) { 1139 u64 l = min(log[i].len, len); 1140 r = log_write(vq->log_base, log[i].addr, l); 1141 if (r < 0) 1142 return r; 1143 len -= l; 1144 if (!len) { 1145 if (vq->log_ctx) 1146 eventfd_signal(vq->log_ctx, 1); 1147 return 0; 1148 } 1149 } 1150 /* Length written exceeds what we have stored. This is a bug. */ 1151 BUG(); 1152 return 0; 1153 } 1154 EXPORT_SYMBOL_GPL(vhost_log_write); 1155 1156 static int vhost_update_used_flags(struct vhost_virtqueue *vq) 1157 { 1158 void __user *used; 1159 if (__put_user(cpu_to_vhost16(vq, vq->used_flags), &vq->used->flags) < 0) 1160 return -EFAULT; 1161 if (unlikely(vq->log_used)) { 1162 /* Make sure the flag is seen before log. */ 1163 smp_wmb(); 1164 /* Log used flag write. */ 1165 used = &vq->used->flags; 1166 log_write(vq->log_base, vq->log_addr + 1167 (used - (void __user *)vq->used), 1168 sizeof vq->used->flags); 1169 if (vq->log_ctx) 1170 eventfd_signal(vq->log_ctx, 1); 1171 } 1172 return 0; 1173 } 1174 1175 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event) 1176 { 1177 if (__put_user(cpu_to_vhost16(vq, vq->avail_idx), vhost_avail_event(vq))) 1178 return -EFAULT; 1179 if (unlikely(vq->log_used)) { 1180 void __user *used; 1181 /* Make sure the event is seen before log. */ 1182 smp_wmb(); 1183 /* Log avail event write */ 1184 used = vhost_avail_event(vq); 1185 log_write(vq->log_base, vq->log_addr + 1186 (used - (void __user *)vq->used), 1187 sizeof *vhost_avail_event(vq)); 1188 if (vq->log_ctx) 1189 eventfd_signal(vq->log_ctx, 1); 1190 } 1191 return 0; 1192 } 1193 1194 int vhost_vq_init_access(struct vhost_virtqueue *vq) 1195 { 1196 __virtio16 last_used_idx; 1197 int r; 1198 bool is_le = vq->is_le; 1199 1200 if (!vq->private_data) { 1201 vhost_reset_is_le(vq); 1202 return 0; 1203 } 1204 1205 vhost_init_is_le(vq); 1206 1207 r = vhost_update_used_flags(vq); 1208 if (r) 1209 goto err; 1210 vq->signalled_used_valid = false; 1211 if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) { 1212 r = -EFAULT; 1213 goto err; 1214 } 1215 r = __get_user(last_used_idx, &vq->used->idx); 1216 if (r) 1217 goto err; 1218 vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx); 1219 return 0; 1220 err: 1221 vq->is_le = is_le; 1222 return r; 1223 } 1224 EXPORT_SYMBOL_GPL(vhost_vq_init_access); 1225 1226 static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, 1227 struct iovec iov[], int iov_size) 1228 { 1229 const struct vhost_memory_region *reg; 1230 struct vhost_memory *mem; 1231 struct iovec *_iov; 1232 u64 s = 0; 1233 int ret = 0; 1234 1235 mem = vq->memory; 1236 while ((u64)len > s) { 1237 u64 size; 1238 if (unlikely(ret >= iov_size)) { 1239 ret = -ENOBUFS; 1240 break; 1241 } 1242 reg = find_region(mem, addr, len); 1243 if (unlikely(!reg)) { 1244 ret = -EFAULT; 1245 break; 1246 } 1247 _iov = iov + ret; 1248 size = reg->memory_size - addr + reg->guest_phys_addr; 1249 _iov->iov_len = min((u64)len - s, size); 1250 _iov->iov_base = (void __user *)(unsigned long) 1251 (reg->userspace_addr + addr - reg->guest_phys_addr); 1252 s += size; 1253 addr += size; 1254 ++ret; 1255 } 1256 1257 return ret; 1258 } 1259 1260 /* Each buffer in the virtqueues is actually a chain of descriptors. This 1261 * function returns the next descriptor in the chain, 1262 * or -1U if we're at the end. */ 1263 static unsigned next_desc(struct vhost_virtqueue *vq, struct vring_desc *desc) 1264 { 1265 unsigned int next; 1266 1267 /* If this descriptor says it doesn't chain, we're done. */ 1268 if (!(desc->flags & cpu_to_vhost16(vq, VRING_DESC_F_NEXT))) 1269 return -1U; 1270 1271 /* Check they're not leading us off end of descriptors. */ 1272 next = vhost16_to_cpu(vq, desc->next); 1273 /* Make sure compiler knows to grab that: we don't want it changing! */ 1274 /* We will use the result as an index in an array, so most 1275 * architectures only need a compiler barrier here. */ 1276 read_barrier_depends(); 1277 1278 return next; 1279 } 1280 1281 static int get_indirect(struct vhost_virtqueue *vq, 1282 struct iovec iov[], unsigned int iov_size, 1283 unsigned int *out_num, unsigned int *in_num, 1284 struct vhost_log *log, unsigned int *log_num, 1285 struct vring_desc *indirect) 1286 { 1287 struct vring_desc desc; 1288 unsigned int i = 0, count, found = 0; 1289 u32 len = vhost32_to_cpu(vq, indirect->len); 1290 struct iov_iter from; 1291 int ret; 1292 1293 /* Sanity check */ 1294 if (unlikely(len % sizeof desc)) { 1295 vq_err(vq, "Invalid length in indirect descriptor: " 1296 "len 0x%llx not multiple of 0x%zx\n", 1297 (unsigned long long)len, 1298 sizeof desc); 1299 return -EINVAL; 1300 } 1301 1302 ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect, 1303 UIO_MAXIOV); 1304 if (unlikely(ret < 0)) { 1305 vq_err(vq, "Translation failure %d in indirect.\n", ret); 1306 return ret; 1307 } 1308 iov_iter_init(&from, READ, vq->indirect, ret, len); 1309 1310 /* We will use the result as an address to read from, so most 1311 * architectures only need a compiler barrier here. */ 1312 read_barrier_depends(); 1313 1314 count = len / sizeof desc; 1315 /* Buffers are chained via a 16 bit next field, so 1316 * we can have at most 2^16 of these. */ 1317 if (unlikely(count > USHRT_MAX + 1)) { 1318 vq_err(vq, "Indirect buffer length too big: %d\n", 1319 indirect->len); 1320 return -E2BIG; 1321 } 1322 1323 do { 1324 unsigned iov_count = *in_num + *out_num; 1325 if (unlikely(++found > count)) { 1326 vq_err(vq, "Loop detected: last one at %u " 1327 "indirect size %u\n", 1328 i, count); 1329 return -EINVAL; 1330 } 1331 if (unlikely(copy_from_iter(&desc, sizeof(desc), &from) != 1332 sizeof(desc))) { 1333 vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", 1334 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1335 return -EINVAL; 1336 } 1337 if (unlikely(desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT))) { 1338 vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", 1339 i, (size_t)vhost64_to_cpu(vq, indirect->addr) + i * sizeof desc); 1340 return -EINVAL; 1341 } 1342 1343 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1344 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1345 iov_size - iov_count); 1346 if (unlikely(ret < 0)) { 1347 vq_err(vq, "Translation failure %d indirect idx %d\n", 1348 ret, i); 1349 return ret; 1350 } 1351 /* If this is an input descriptor, increment that count. */ 1352 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1353 *in_num += ret; 1354 if (unlikely(log)) { 1355 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1356 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1357 ++*log_num; 1358 } 1359 } else { 1360 /* If it's an output descriptor, they're all supposed 1361 * to come before any input descriptors. */ 1362 if (unlikely(*in_num)) { 1363 vq_err(vq, "Indirect descriptor " 1364 "has out after in: idx %d\n", i); 1365 return -EINVAL; 1366 } 1367 *out_num += ret; 1368 } 1369 } while ((i = next_desc(vq, &desc)) != -1); 1370 return 0; 1371 } 1372 1373 /* This looks in the virtqueue and for the first available buffer, and converts 1374 * it to an iovec for convenient access. Since descriptors consist of some 1375 * number of output then some number of input descriptors, it's actually two 1376 * iovecs, but we pack them into one and note how many of each there were. 1377 * 1378 * This function returns the descriptor number found, or vq->num (which is 1379 * never a valid descriptor number) if none was found. A negative code is 1380 * returned on error. */ 1381 int vhost_get_vq_desc(struct vhost_virtqueue *vq, 1382 struct iovec iov[], unsigned int iov_size, 1383 unsigned int *out_num, unsigned int *in_num, 1384 struct vhost_log *log, unsigned int *log_num) 1385 { 1386 struct vring_desc desc; 1387 unsigned int i, head, found = 0; 1388 u16 last_avail_idx; 1389 __virtio16 avail_idx; 1390 __virtio16 ring_head; 1391 int ret; 1392 1393 /* Check it isn't doing very strange things with descriptor numbers. */ 1394 last_avail_idx = vq->last_avail_idx; 1395 if (unlikely(__get_user(avail_idx, &vq->avail->idx))) { 1396 vq_err(vq, "Failed to access avail idx at %p\n", 1397 &vq->avail->idx); 1398 return -EFAULT; 1399 } 1400 vq->avail_idx = vhost16_to_cpu(vq, avail_idx); 1401 1402 if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) { 1403 vq_err(vq, "Guest moved used index from %u to %u", 1404 last_avail_idx, vq->avail_idx); 1405 return -EFAULT; 1406 } 1407 1408 /* If there's nothing new since last we looked, return invalid. */ 1409 if (vq->avail_idx == last_avail_idx) 1410 return vq->num; 1411 1412 /* Only get avail ring entries after they have been exposed by guest. */ 1413 smp_rmb(); 1414 1415 /* Grab the next descriptor number they're advertising, and increment 1416 * the index we've seen. */ 1417 if (unlikely(__get_user(ring_head, 1418 &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) { 1419 vq_err(vq, "Failed to read head: idx %d address %p\n", 1420 last_avail_idx, 1421 &vq->avail->ring[last_avail_idx % vq->num]); 1422 return -EFAULT; 1423 } 1424 1425 head = vhost16_to_cpu(vq, ring_head); 1426 1427 /* If their number is silly, that's an error. */ 1428 if (unlikely(head >= vq->num)) { 1429 vq_err(vq, "Guest says index %u > %u is available", 1430 head, vq->num); 1431 return -EINVAL; 1432 } 1433 1434 /* When we start there are none of either input nor output. */ 1435 *out_num = *in_num = 0; 1436 if (unlikely(log)) 1437 *log_num = 0; 1438 1439 i = head; 1440 do { 1441 unsigned iov_count = *in_num + *out_num; 1442 if (unlikely(i >= vq->num)) { 1443 vq_err(vq, "Desc index is %u > %u, head = %u", 1444 i, vq->num, head); 1445 return -EINVAL; 1446 } 1447 if (unlikely(++found > vq->num)) { 1448 vq_err(vq, "Loop detected: last one at %u " 1449 "vq size %u head %u\n", 1450 i, vq->num, head); 1451 return -EINVAL; 1452 } 1453 ret = __copy_from_user(&desc, vq->desc + i, sizeof desc); 1454 if (unlikely(ret)) { 1455 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 1456 i, vq->desc + i); 1457 return -EFAULT; 1458 } 1459 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) { 1460 ret = get_indirect(vq, iov, iov_size, 1461 out_num, in_num, 1462 log, log_num, &desc); 1463 if (unlikely(ret < 0)) { 1464 vq_err(vq, "Failure detected " 1465 "in indirect descriptor at idx %d\n", i); 1466 return ret; 1467 } 1468 continue; 1469 } 1470 1471 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 1472 vhost32_to_cpu(vq, desc.len), iov + iov_count, 1473 iov_size - iov_count); 1474 if (unlikely(ret < 0)) { 1475 vq_err(vq, "Translation failure %d descriptor idx %d\n", 1476 ret, i); 1477 return ret; 1478 } 1479 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { 1480 /* If this is an input descriptor, 1481 * increment that count. */ 1482 *in_num += ret; 1483 if (unlikely(log)) { 1484 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 1485 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 1486 ++*log_num; 1487 } 1488 } else { 1489 /* If it's an output descriptor, they're all supposed 1490 * to come before any input descriptors. */ 1491 if (unlikely(*in_num)) { 1492 vq_err(vq, "Descriptor has out after in: " 1493 "idx %d\n", i); 1494 return -EINVAL; 1495 } 1496 *out_num += ret; 1497 } 1498 } while ((i = next_desc(vq, &desc)) != -1); 1499 1500 /* On success, increment avail index. */ 1501 vq->last_avail_idx++; 1502 1503 /* Assume notifications from guest are disabled at this point, 1504 * if they aren't we would need to update avail_event index. */ 1505 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 1506 return head; 1507 } 1508 EXPORT_SYMBOL_GPL(vhost_get_vq_desc); 1509 1510 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ 1511 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n) 1512 { 1513 vq->last_avail_idx -= n; 1514 } 1515 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc); 1516 1517 /* After we've used one of their buffers, we tell them about it. We'll then 1518 * want to notify the guest, using eventfd. */ 1519 int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) 1520 { 1521 struct vring_used_elem heads = { 1522 cpu_to_vhost32(vq, head), 1523 cpu_to_vhost32(vq, len) 1524 }; 1525 1526 return vhost_add_used_n(vq, &heads, 1); 1527 } 1528 EXPORT_SYMBOL_GPL(vhost_add_used); 1529 1530 static int __vhost_add_used_n(struct vhost_virtqueue *vq, 1531 struct vring_used_elem *heads, 1532 unsigned count) 1533 { 1534 struct vring_used_elem __user *used; 1535 u16 old, new; 1536 int start; 1537 1538 start = vq->last_used_idx & (vq->num - 1); 1539 used = vq->used->ring + start; 1540 if (count == 1) { 1541 if (__put_user(heads[0].id, &used->id)) { 1542 vq_err(vq, "Failed to write used id"); 1543 return -EFAULT; 1544 } 1545 if (__put_user(heads[0].len, &used->len)) { 1546 vq_err(vq, "Failed to write used len"); 1547 return -EFAULT; 1548 } 1549 } else if (__copy_to_user(used, heads, count * sizeof *used)) { 1550 vq_err(vq, "Failed to write used"); 1551 return -EFAULT; 1552 } 1553 if (unlikely(vq->log_used)) { 1554 /* Make sure data is seen before log. */ 1555 smp_wmb(); 1556 /* Log used ring entry write. */ 1557 log_write(vq->log_base, 1558 vq->log_addr + 1559 ((void __user *)used - (void __user *)vq->used), 1560 count * sizeof *used); 1561 } 1562 old = vq->last_used_idx; 1563 new = (vq->last_used_idx += count); 1564 /* If the driver never bothers to signal in a very long while, 1565 * used index might wrap around. If that happens, invalidate 1566 * signalled_used index we stored. TODO: make sure driver 1567 * signals at least once in 2^16 and remove this. */ 1568 if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old))) 1569 vq->signalled_used_valid = false; 1570 return 0; 1571 } 1572 1573 /* After we've used one of their buffers, we tell them about it. We'll then 1574 * want to notify the guest, using eventfd. */ 1575 int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads, 1576 unsigned count) 1577 { 1578 int start, n, r; 1579 1580 start = vq->last_used_idx & (vq->num - 1); 1581 n = vq->num - start; 1582 if (n < count) { 1583 r = __vhost_add_used_n(vq, heads, n); 1584 if (r < 0) 1585 return r; 1586 heads += n; 1587 count -= n; 1588 } 1589 r = __vhost_add_used_n(vq, heads, count); 1590 1591 /* Make sure buffer is written before we update index. */ 1592 smp_wmb(); 1593 if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) { 1594 vq_err(vq, "Failed to increment used idx"); 1595 return -EFAULT; 1596 } 1597 if (unlikely(vq->log_used)) { 1598 /* Log used index update. */ 1599 log_write(vq->log_base, 1600 vq->log_addr + offsetof(struct vring_used, idx), 1601 sizeof vq->used->idx); 1602 if (vq->log_ctx) 1603 eventfd_signal(vq->log_ctx, 1); 1604 } 1605 return r; 1606 } 1607 EXPORT_SYMBOL_GPL(vhost_add_used_n); 1608 1609 static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1610 { 1611 __u16 old, new; 1612 __virtio16 event; 1613 bool v; 1614 /* Flush out used index updates. This is paired 1615 * with the barrier that the Guest executes when enabling 1616 * interrupts. */ 1617 smp_mb(); 1618 1619 if (vhost_has_feature(vq, VIRTIO_F_NOTIFY_ON_EMPTY) && 1620 unlikely(vq->avail_idx == vq->last_avail_idx)) 1621 return true; 1622 1623 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1624 __virtio16 flags; 1625 if (__get_user(flags, &vq->avail->flags)) { 1626 vq_err(vq, "Failed to get flags"); 1627 return true; 1628 } 1629 return !(flags & cpu_to_vhost16(vq, VRING_AVAIL_F_NO_INTERRUPT)); 1630 } 1631 old = vq->signalled_used; 1632 v = vq->signalled_used_valid; 1633 new = vq->signalled_used = vq->last_used_idx; 1634 vq->signalled_used_valid = true; 1635 1636 if (unlikely(!v)) 1637 return true; 1638 1639 if (__get_user(event, vhost_used_event(vq))) { 1640 vq_err(vq, "Failed to get used event idx"); 1641 return true; 1642 } 1643 return vring_need_event(vhost16_to_cpu(vq, event), new, old); 1644 } 1645 1646 /* This actually signals the guest, using eventfd. */ 1647 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1648 { 1649 /* Signal the Guest tell them we used something up. */ 1650 if (vq->call_ctx && vhost_notify(dev, vq)) 1651 eventfd_signal(vq->call_ctx, 1); 1652 } 1653 EXPORT_SYMBOL_GPL(vhost_signal); 1654 1655 /* And here's the combo meal deal. Supersize me! */ 1656 void vhost_add_used_and_signal(struct vhost_dev *dev, 1657 struct vhost_virtqueue *vq, 1658 unsigned int head, int len) 1659 { 1660 vhost_add_used(vq, head, len); 1661 vhost_signal(dev, vq); 1662 } 1663 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal); 1664 1665 /* multi-buffer version of vhost_add_used_and_signal */ 1666 void vhost_add_used_and_signal_n(struct vhost_dev *dev, 1667 struct vhost_virtqueue *vq, 1668 struct vring_used_elem *heads, unsigned count) 1669 { 1670 vhost_add_used_n(vq, heads, count); 1671 vhost_signal(dev, vq); 1672 } 1673 EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); 1674 1675 /* return true if we're sure that avaiable ring is empty */ 1676 bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1677 { 1678 __virtio16 avail_idx; 1679 int r; 1680 1681 r = __get_user(avail_idx, &vq->avail->idx); 1682 if (r) 1683 return false; 1684 1685 return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx; 1686 } 1687 EXPORT_SYMBOL_GPL(vhost_vq_avail_empty); 1688 1689 /* OK, now we need to know about added descriptors. */ 1690 bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1691 { 1692 __virtio16 avail_idx; 1693 int r; 1694 1695 if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) 1696 return false; 1697 vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; 1698 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1699 r = vhost_update_used_flags(vq); 1700 if (r) { 1701 vq_err(vq, "Failed to enable notification at %p: %d\n", 1702 &vq->used->flags, r); 1703 return false; 1704 } 1705 } else { 1706 r = vhost_update_avail_event(vq, vq->avail_idx); 1707 if (r) { 1708 vq_err(vq, "Failed to update avail event index at %p: %d\n", 1709 vhost_avail_event(vq), r); 1710 return false; 1711 } 1712 } 1713 /* They could have slipped one in as we were doing that: make 1714 * sure it's written, then check again. */ 1715 smp_mb(); 1716 r = __get_user(avail_idx, &vq->avail->idx); 1717 if (r) { 1718 vq_err(vq, "Failed to check avail idx at %p: %d\n", 1719 &vq->avail->idx, r); 1720 return false; 1721 } 1722 1723 return vhost16_to_cpu(vq, avail_idx) != vq->avail_idx; 1724 } 1725 EXPORT_SYMBOL_GPL(vhost_enable_notify); 1726 1727 /* We don't need to be notified again. */ 1728 void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) 1729 { 1730 int r; 1731 1732 if (vq->used_flags & VRING_USED_F_NO_NOTIFY) 1733 return; 1734 vq->used_flags |= VRING_USED_F_NO_NOTIFY; 1735 if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) { 1736 r = vhost_update_used_flags(vq); 1737 if (r) 1738 vq_err(vq, "Failed to enable notification at %p: %d\n", 1739 &vq->used->flags, r); 1740 } 1741 } 1742 EXPORT_SYMBOL_GPL(vhost_disable_notify); 1743 1744 static int __init vhost_init(void) 1745 { 1746 return 0; 1747 } 1748 1749 static void __exit vhost_exit(void) 1750 { 1751 } 1752 1753 module_init(vhost_init); 1754 module_exit(vhost_exit); 1755 1756 MODULE_VERSION("0.0.1"); 1757 MODULE_LICENSE("GPL v2"); 1758 MODULE_AUTHOR("Michael S. Tsirkin"); 1759 MODULE_DESCRIPTION("Host kernel accelerator for virtio"); 1760